A Comparison of Porous Layer Open Tubular (PLOT) Columns for the Separation of Refinery Gases
R. Wiedemer, S. Adams, T. Edge, R. Bunn
Overview
This poster demonstrates the use of various Thermo Scientific TracePLOT Porous Layer Open
Tubular columns for the analysis of low molecular weight hydrocarbons.
Introduction
Porous Layer Open Tubular (PLOT) columns are well suited for the analysis of light
hydrocarbons such as those found in refinery gases. These highly selective columns are
capable of separating low molecular weight hydrocarbons at above ambient temperatures and
the columns can then be programmed to higher temperatures to elute higher boiling
compounds. An increasingly wide variety of PLOT column coatings are available, including
alumina deactivated with Na2SO4 and with KCl, as well as a range of porous polymers with
varying degrees of polarity
polarity.
Thermo Fisher Scientific, Bellefonte, PA, USA
TracePLOT Alumina Columns
Alumina is often used for the analysis of volatile hydrocarbons due to its selectivity which
provides baseline resolution of most isomers at above ambient temperatures. The highly
retentive nature of alumina requires that the surface be deactivated with inorganic salts such
as sodium sulfate or potassium chloride to control retention.
Note the difference in selectivity between the alumina deactivated with Na2SO4 (Figure 1)
versus the alumina KCl (Figure 2) deactivation. For example alumina Na2SO4 elutes
propadiene and acetylene after butane while alumina KCl elutes acetylene before propadiene
and butanes. Not shown in these chromatograms, alumina Na2SO4 elutes methyl acetylene
(a.k.a. propyne) after 1,3-butadiene, while alumina KCl elutes methyl acetylene before 1,3butadiene.
Column: TracePLOT TG-BOND Alumina KCl,
30m x 0.53mm ID x 20um
Sample – Refinery Gas #5
Injection – 10l (manual-syringe)
Split injection
Split flow - 52mL/min (Split ratio 13:1)
Liner – 3mm FocusLiner, straight, no glass
wool
Injector Temperature - 200°C
Carrier Gas – Helium, Constant Flow at
4.0mL/minute
Oven Program - 50°C (2 min)-200°C (3min) at
10°C/min
Detection – FID 250°C.
FIGURE 1. TracePLOT™ TG-BOND Alumina Na2SO4- Refinery Gas
1. Methane
2. Ethane
3. Ethylene
4. Propane
5. Propylene
6. Isobutane
7. n-Butane
8. Propadiene
y
9. Acetylene
10. trans-2-Butene
11. 1-Butene
12. Isobutylene
13. cis-2-Butene
14. Isopentane
15. n-Pentane
16. 1,3-Butadiene
1,3 Butadiene
17. trans-2-Pentene
18. 2-Methyl-2-butene
19. 1-Pentene
20. cis-2-Pentene
Instrument – TRACE GC Ultra
Column: TracePLOT TG-BOND Q+,
30m x 0.53mm ID x 20um
Sample – Refinery Gas #5
Injection – 10l (manual-syringe)
Split injection
Split flow - 52mL/min (Split ratio 13:1)
Liner – 3mm FocusLiner, straight, no glass
wool
Injector Temperature - 200°C
Carrier Gas – Helium, Constant Flow at
4.0mL/minute
Oven Program - 50°C (2 min) - 200°C (3min)
at 10°C/min
Detection – FID 250°C
Column: TracePLOT TG-BOND Q,
30m x 0.53mm ID x 20um
Sample – Refinery Gas #5
Injection – 10l (manual-syringe)
Split injection
Split flow - 52mL/min (Split ratio 13:1)
Liner – 3mm FocusLiner, straight, no glass wool
Injector Temperature - 200°C
Carrier Gas – Helium, Constant Flow at
4.0mL/minute
Oven Program - 50°C (2 min) - 200°C (3min) at
10°C/min
Detection – FID 250°C
Instrument – TRACE™ GC Ultra
Results
Column: TracePLOT TG-BOND Alumina
Na2SO4, 30m x 0.53mm ID x 20um
Sample – Refinery Gas #5
Injection – 10l (manual-syringe)
Split injection
Split flow - 52mL/min (Split ratio 13:1)
Liner – 3mm FocusLiner, straight, no glass
wool
Injector Temperature - 200°C
Carrier Gas – Helium, Constant Flow at
4.0mL/minute
Oven Program - 50°C (2 min) - 200°C (3min)
at 10°C/min
Detection – FID 250°C.
FIGURE 5. TraceGOLD TG-BOND Q - Refinery Gas
Instrument – TRACE GC Ultra
FIGURE 2. TracePLOT TG-BOND Alumina KCl - Refinery Gas
The differences in selectivity of numerous types of Thermo Scientific TracePLOT columns are
demonstrated by the differences in the separation of light hydrocarbons in a refinery gas
sample.
Instrument – Thermo Scientific TRACE GC
Ultra
FIGURE 3. TraceGOLD TG-BOND Q+ - Refinery Gas
1. Methane
2. Ethane
y
3. Ethylene
4. Propane
5. Propylene
6. Acetylene
7. Isobutane
8. Propadiene
9. n-Butane
10. trans-2-Butene
trans 2 Butene
11. 1-Butene
12. Isobutylene
13. cis-2-Butene
14. Isopentane
1. Methane
2. Ethylene
3. Acetylene
4. Ethane
5. Propylene
6. Propane
7. Propadiene
8. Isobutane
9. Isobutylene
10. 1-Butene
11. 1,3-Butadiene
12. n-Butane
13. cis-2-Butene
14. trans-2-Butene
1. Methane
2. Ethylene
3. Acetylene
4. Ethane
5. Propylene
6. Propane
7. Propadiene
8. Isobutane
9. Isobutylene
10. 1-Butene
11. 1,3-Butadiene
12. n-Butane
13. cis-2-Butene
14. trans-2-Butene
15. Isopentane
16. 1-Pentene
17. trans-2-Pentene
18. n-Pentane
19. cis-2-Pentene
20. 2-Methyl-2-butene
FIGURE 4. TraceGOLD TG-BOND S - Refinery Gas
Conclusions
15. n-Pentane
16. 1,3-Butadiene
17. trans-2-Pentene
18. 2-Methyl-2-butene
19. 1-Pentene
20. cis-2-Pentene
TracePLOT Porous Polymer Columns
Three porous polymer PLOT columns were used for the analysis of a refinery gas sample.
TracePLOT TG-BOND Q+ (Figure 3) is a porous divinyl benzene homopolymer of
intermediate polarity incorporating a lower amount 4-vinyl pyridine into the polymer.
TracePLOT TG-BOND S (Figure 4) is a midpolarity divinylbenzene incorporating higher
amount of 4-vinyl pyridine. TracePLOT TG-BOND Q (Figure 5) is a non-polar 100%
divinylbenzene polymer. These three different types of porous polymers show significant
changes in elution order as compared to the two alumina PLOT columns. This would be
useful for p
purity
y analysis
y of a specific
p
hydrocarbon
y
in situations where an impurity
p y elutes after
the main peak of interest on an alumina column, which can cause in the impurity to be
overrun by the main peak, resulting in co-elution. The differences in selectivity between these
columns does not result in elution order changes between these three porous polymer PLOT
columns, but there are differences in separation factor for many of the components.
1 Isopentane
15.
16. 1-Pentene
17. trans-2-Pentene
18. n-Pentane
19. cis-2-Pentene
20. 2-Methyl-2-butene
Instrument – TRACE GC Ultra
Column: TracePLOT TG-BOND S,
30m x 0.53mm ID x 20um
Sample – Refinery Gas #5
Injection – 10l (manual-syringe)
Split injection
Split flow - 52mL/min (Split ratio 13:1)
Liner – 3mm FocusLiner, straight, no glass wool
Injector Temperature - 200°C
Carrier Gas – Helium, Constant Flow at
4.0mL/minute
Oven Program - 50°C (2 min) - 200°C (3min) at
10°C/min
Detection – FID 250°C.
• Separation
p
of saturated,, unsaturated and branched chain light
g hydrocarbons
y
such as those
found in refinery gases is best accomplished on deactivated alumina PLOT columns.
• Porous polymers PLOT columns offer a different selectivity and elution order for refinery gas
components versus alumina which may be useful for purity analysis of individual
hydrocarbons.
For additional information, please visit our Chromatography Resource Centre which can be
found at: www.thermoscientific.com/chromatography
1. Methane
2. Ethylene
3. Acetylene
4. Ethane
5. Propylene
6. Propane
7. Propadiene
8. Isobutane
9. Isobutylene
10. 1-Butene
11. 1,3-Butadiene
12. n-Butane
13. cis-2-Butene
14. trans-2-Butene
15. Isopentane
16. 1-Pentene
17. trans-2-Pentene
18. n-Pentane
19. cis-2-Pentene
20. 2-Methyl-2-butene
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